Vandaceous orchids do not refer to Vandas exclusively. Vandaceous orchids actually comprise of a much larger variety of orchids – just that they are close relatives to the vanda; with comparable characteristics (Sun-loving, monopodial, etc). Some would also use the term “vanda alliances” to refer to such Orchids. Just to name a few that are cultivated in Toh Garden : Ascocenda, Mokara, Renanthera, Vanda, Aranthera, Holtummarra, etc.
Vandaceous – Basics
Sunlight (70 ~ 100% daily) :
Vandaceous orchids typically require more sunlight than other types of orchids to grow well and flower. Technically, they need full sunlight, but for optimization, it would be prudent to identity the amount of sunlight required for each type of plant. Simply generalizing them based on their genus (sub-species) may not be ideal. (In the first place, telling apart Mokaras, Ascocenda, Vandas, etc poses certain difficulty). As such, a simpler way to gauge would be based on the plants’ type of leaf.
As illustrated in diagram above – vandaceous leaves fall between a spectrum of “strap” and “terete”. Strapped leaves are broad and flat; while teret leaves are thick and cylindrical (pencil-like). Typically, more “terete leafed” vandaceous orchids are adept at growing in full sunlight; while certain “strap leafed” vandaceous orchids may prefer partial sunlight. Unless the leaves show signs of sunburn (yellowing); vandaceous orchids are likely to thrive well in as much sunlight as possible. Not to mention, certain vandaceous orchids (eg: mokaras) do not thrive well in full sunlight when they are young / or recently re-planted; but will adapt to more or even full sunlight when they become more matured. Prior to subjecting a vandaceous orchid to partial/full sunlight, consider the following : (1) type of leaves & (2) stage of maturity
How much and how often one waters the plant would depend on the pot-medium and environmental factors. However, one rule of thumb for all Orchids still apply : watering too much is far more dangerous than watering too little. While certain Orchids prefer to be in moist medium at all times, vandaceous plants will do fine in medium that is periodically dry in a day. If watering is inadequate, the plant would look wrinkled – simply increase the frequency and/or amount for watering gradually, and plant would be back in good shape. Since vandaceous plants are typically basked in more sunlight, watering to the roots / base of the plant should be done during times of the day whereby sunlight is mild (approx. 8 ~ 10 am ; 4 ~ 5 pm ). There are several reasons for watering at such times:
(1) Maximize absorption during time of the day where the plant is actively making food
(2) Allow enough time for excess water to evaporate & not stagnant overnight
(3) Prevents “shock” to the plant – splashing a heated-up plant (especially in the mid-day sun) with cool / cold water would induce stress
Vandaceous – Advanced
The “crown” of the vandaceous orchid is the starting point of all its vegetative growth. But if crown-rot occurs, the plant will cease to grow any further. As such, preventive measures will be highlighted and avenues to salvage the situation would be revealed thereafter. Primarily, excess moisture / water that stagnant in the crown inclines crown rot (strapped / quarter terete leafed plants are highly vulnerable). As mentioned in the basics for watering – water at appropriate times, such that excess water can be evaporated by nightfall. Not to mention, avoid watering onto/into the crown of the plant – to prevent water from accumulating in the crown; and prevent physical trauma to the delicate crown. Another drastic measure would be to absorb excess water collected in the crown with cotton / tissue – this is a especially applicable during the monsoon season where raining persist.
In the event of crown-rot, the crown becomes soggy and seemingly decomposed. The only remedy (or rather, damage-control) is to removed the crown completely, so that the rest of the plant does not get infected / or become a hotbed for fungus and pathogens.
One way would be to pull out the infected crown, the other course of action would be to cut off the top portion of of the plant – leaving behind a stump; and treating the open wounds with fungicide.
With the lack of a crown growth, the plant’s survival instinct would be triggered, thereby producing keikis (baby plants). This is akin to methods in vegetative propagation (refer to “Producing Orchid Keikis“).
The managements of vandaceous keikis or top-cuts is perhaps, one of the most received queries till date. Notably, vandaceous plants take a long time to re-establish themselves in a new pot ( between 6 ~ 8 months). A recommendation would be that top-cuts should come with at least 2 ~ 3 roots. (Only in most ideal conditions – top-cuts can be planted even without roots). Given the extensive time needed for re-establishment & stabilization, it would be ideal such that the top-cut is firmly secured (kept stationary) in the new medium. The following diagram illustrates the procedures for planting a Mokara top-cut with wood-chips.
Pot mediums such as wood-chip and sphagnum moss can be compressed to increase stability – though they are prone to water retention. Pot medium like charcoal does not retain too much water, but stability of the plant’s position may be compromised. Otherwise, some may prefer a mixture of pot mediums.